Cannot create an ASG from scratch - "invalid new value for .tags: length changed from 1 to 2"

[marcinwyszynski]

Description

I'm authoring a module that uses this module. I want to support configuring the HTTP metadata endpoint, which requires bumping the major to "4", and even with a clean install this seems broken with the recent AWS provider:

module.this.aws_iam_instance_profile.this: Creation complete after 1s [id=sp5ft-sound-duckling]
╷
│ Error: Provider produced inconsistent final plan
│ 
│ When expanding the plan for
│ module.this.module.asg.aws_autoscaling_group.this[0] to include new values
│ learned so far during apply, provider "registry.terraform.io/hashicorp/aws"
│ produced an invalid new value for .tags: length changed from 1 to 2.
│ 
│ This is a bug in the provider, which should be reported in the provider's
│ own issue tracker.

Versions

• Terraform: 0.15.1
• Provider(s): AWS - v3.39.0
• Module: 4.1.0

Reproduction

The full repro code can be found here. Since the is another module, the Terraform entry point (test case) is specified here.

Steps to reproduce the behavior:

Are you using workspaces?: no Have you cleared the local cache (see Notice section above)?: yes List steps in order that led up to the issue you encountered:

• terraform plan -out plan.bin
• terraform apply -auto-approve plan.bin

Expected behavior

The module applies cleanly.

Actual behavior

The module does not apply cleanly.

Terminal Output Screenshot(s)

[antonbabenko]

Hi Marcin,

I checked the issue you have with your module and here are the missing bits:

1. Missing create_lt = true and use_lt = true in asg.tf.
2. tags contains an unknown value (coming from random_pet), so the length of tags changes as Terraform progressing the creation of the resources. It is weird, I know.
3. The easiest solution is to use tags_as_map argument of this module and pass as key/value instead of lists of dynamic length:

   
   module "asg" {
   # omitted...
   tags_as_map = merge(var.tags_as_map, { WorkerPoolID = var.worker_pool_id })
   }

variable "tags_as_map" { type = map(string) default = {} }

This way module will make sure that tags are processed at the beginning and length will not change.

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